Background/Aims  Musculoskeletal ultrasound (MSUS) has utility in optimising the use of conventional synthetic disease-modifying antirheumatic drugs (csDMARDs) and biologic DMARDs (bDMARDs) in patients with inflammatory arthritis. However, it is unclear whether this is useful among patients with concomitant chronic pain and/or fibromyalgia, who often have elevated disease activity scores. We aimed to evaluate the impact of MSUS on inflammatory arthritis patients with concomitant chronic pain and/or fibromyalgia who met criteria for treatment escalation in a district general rheumatology service. Methods  We conducted a retrospective audit of inflammatory arthritis patients with concomitant chronic pain and/or fibromyalgia who were eligible for DMARD escalation and underwent a MSUS since 2017. Scanning was performed by either a trained rheumatologist or musculoskeletal ultrasonographer. Synovitis was assessed following OMERACT guidelines. Results  43 patients with inflammatory arthritis and concomitant chronic pain and/or fibromyalgia who underwent MSUS were identified. The mean age was 57.0 years (SD 15.6), and 34 patients (79%) were female. Rheumatoid arthritis was the most frequent diagnosis with 32 patients (74%), with psoriatic arthritis in 5 (12%), undifferentiated inflammatory arthritis in 4 (9%) and axial spondylarthritis (axSpA) in 2 (5%). 20 patients (47%) had a concurrent diagnosis of fibromyalgia. The median tender joint count among non-axSpA patients was 10 (IQR 4-15) and 2 (IQR 0-4) for swollen joints. MSUS was requested for consideration of a bDMARD switch in 21 patients (49%), a new bDMARD in 15 (35%), and starting an adjunctive csDMARD among 7 (16%). 34 patients (79%) were already established on csDMARDs, with 15 patients (35%) being on one or more, and methotrexate being the most prescribed csDMARD in 26 (76%). 14 patients (33%) were already established on bDMARDs, 9 (21%) had been on them previously and 20 (47%) were bDMARD naïve. Among those on bDMARDs, anti-TNFs agents were the most prescribed (71%). Active synovitis was identified in 17 patients (40%). Greyscale synovitis, tenosynovitis and enthesitis were seen in 30 (70%), 10 (23%) and 2 patients (5%), respectively. Erosions were identified in 12 patients (28%), with 2 (17%) having new erosions. 27 patients (63%) had either a csDMARD started (n = 7, 33%), or a bDMARD started (n = 11, 31%) or switched (n = 9, 25%) after MSUS. Those with fibromyalgia were less likely to start or switch DMARDs (8/20 patients, 40%) than those without (19/23 patients, 82.6%), Pchi-squared = 0.004. Furthermore, active synovitis on MSUS was associated with DMARD escalation (14/17 patients [82.4%] with synovitis versus 13/26 patients [50%] without; Pchi-squared = 0.03). Conclusion  MSUS avoided unnecessary DMARD escalation in a significant proportion of patients with inflammatory arthritis and features of concomitant chronic pain and/or fibromyalgia (n = 26, 37%), potentially resulting in reduced patient exposure to harmful DMARD side effects, and cost savings for the service. Disclosure  M. Chen-Xu: None. D. Hyseni: None. K. Achilleos: None.